Depilatory compositions are cosmetic hair removal formulations. They comprise keratin reducing agents, which attack the disulphide bonds in hair to weaken it, such that subsequent gentle scraping and/or wiping completes severance of the hair from the skin and effects hair removal. Commercially, the most common keratin reducing agents are thioglycolates, which are typically formulated at high pH. An unwanted side effect of chemical depilation is that the depilatory composition comes into contact with and must have a relatively long residence time on skin to achieve effective hair removal and this long residence time combined with the alkaline conditions needed for effective hair removal may give rise to skin irritation.
The above problem has been recognized in the art. Reference is made to US 2004/0219118, which discloses treatment with a “lipophilic” material before application of a thioglycolate-based reactive depilatory composition. Lipophilic materials exemplified in this patent application are oils, such as mineral oil. As shown hereinbelow, the present applicants have tested a range of lipophilic materials to determine their ability to prevent thioglycolate penetration and, thereby, their ability to reduce or prevent skin irritation Applicants have surprisingly found that oils, such as mineral oil, have no or a low ability to prevent thioglycolate penetration to the skin. There thus exists a need to develop a pre-treatment composition which better reduces skin irritation.